Linux ATA RAID HOWTO

Murty Rompalli

           murty@solar.m u r t y.net
        

May 15, 2002

Revision History
Revision 2.12002-09-07Revised by: mr
Minor enhancements
Revision 2.02002-05-10Revised by: mr
Major enhancements
Revision 1.32002-05-07Revised by: jyg
format fixes
Revision 1.22002-04-30Revised by: mr
Minor fixes
Revision 1.12002-04-28Revised by: ldl
Some minor changes and sgml-improvements
Revision 1.02002-04-26Revised by: mr
Initial Release

RAID is not limited to expensive SCSI disks anymore as more and more motherboard manufacturers are introducing motherboards with onboard RAID support for inexpensive IDE disks, known as ATA RAID. Promise Technolgy and HighPoint are two companies that dominate this ATA RAID market. This HOWTO document explains how to install Linux on an Intel Pentium compatible computer with an ATA RAID Controller (onboard chip or seperate card), single or multiple processors and atleast two hard disks. Currently, this document covers installing RedHat Linux 7.3 with Promise FastTrak ATA RAID Controller. Appendix at the end briefly explains how to install on a system with HighPoint HPT instead of Promise FastTrak RAID.


Introduction

The goal of this HOWTO document is to explain how to setup RAID 1 (mirroring) with the two hard disks and install bootable RedHat Linux Operating System on the mirror device. This document discusses both methods of achieving this goal: 1. Using Promise supplied driver 2. Using Linux native RAID. If you choose the first method (using Promise supplied driver), you must use the Kernel that comes with RedHat 7.3 CD. If you choose the second method, you can upgrade the kernel to the latest kernel. This document does not discuss Striping or other disk configurations, although the author believes that this document might help setup those configurations. This document does not yet cover: 1. Installation using GRUB instead of LILO and 2. Installation with Latest development kernels (2.5.x). Although this document focusses on Promise FastTrak RAID, Appendix at the end of the document explains how to use this document to install Red Hat Linux on computers with HighPoint HPT RAID.

First of all we need a bit of legalese. Recent development shows it is quite important.


Copyright Information

© 2002 Murty Rompalli

This document is copyrighted © 2002 Murty Rompalli and is distributed under the terms of the GNU Free Documentation License and additional terms described below.

This Linux HOWTO document may be reproduced and distributed in whole or in part, in any medium physical or electronic, as long as this copyright notice is retained on all copies. Commercial redistribution is allowed and encouraged; however, the author would like to be notified of any such distributions.

All translations, derivative works, or aggregate works incorporating this Linux HOWTO document must be covered under this copyright notice. That is, you may not produce a derivative work from this HOWTO document and impose additional restrictions on its distribution. Exceptions to these rules may be granted under certain conditions; please contact the Linux HOWTO coordinator at this address .

In short, the author wishes to promote dissemination of this information through as many channels as possible but wish to retain copyright on this HOWTO document, and would like to be notified of any plans to redistribute this HOWTO document.


Disclaimer

No liability for the contents of this documents can be accepted. Use the concepts, examples and other content at your own risk. As this is a new edition of this document, there may be errors and inaccuracies, that may of course be damaging to your system. Proceed with caution, and although this is highly unlikely, the author does not take any responsibility for that.

All copyrights are held by their respective owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark.

Naming of particular products or brands should not be seen as endorsements.

You are strongly recommended to take a backup of your system before major installation and backups at regular intervals.


New Version

The newest version of this HOWTO will always be made available on my website http://www.murty.net/ataraid/, or you may contact me directly at to check if there is a newer version.


Printer Friendly Versions

Currently, this document is available in the following formats:

Note that paper sizes vary in the world, A4 and US letter differ significantly. You might also wish to consider using the universal format (8.27x11in; 210x279mm).


Credits

Your name here, if you contribute :)

Luc de Louw <luc at delouw.ch> corrected errors in my SGML source.

Joy Y Goodreau <joyg at us.ibm.com> corrected errors in my SGML source.

In this version I have the pleasure of acknowledging:

Alain Portal <aportal at univ-montp2.fr>, Service Commun de Microscopie Electronique for proof-reading and correcting mistakes.


Feedback

Feedback is most certainly welcome for this document. Without your submissions and input, this document wouldn't exist. Please send your additions, comments and criticisms to the following email address : .


Translations

Please help International users who do not speak English. You are encouraged to translate this document to a foreign language. Please notify the author if you translated or would like to translate this document into a foreign language. The following translation efforts are already under way.


Requirements

This section lists what items are required before you start installing on your computer.


Prepare Promise Driver Floppy

  1. Download Combined zip file from the following link. You can do this on any computer connected to Internet. This file has two zip files: one for multiprocessor computers (rhsmp.zip) and other for single processor computers (rhup.zip). Pick the right zip file for your machine and save it to a dos formatted floppy

  2. Insert this floppy into a working Linux computer and type:

    mount /dev/fd0 /mnt/floppy 
    cd /mnt/floppy 
    mv rhsmp-ftb22.zip /tmp 
    unzip /tmp/rhsmp-ftb22.zip 
    cd / 
    umount /mnt/floppy

    NOTE: The above commands are for multiprocessor computers. Adjust above commands by replacing rhsmp by rhup if your computer has only one processor.

  3. Label the floppy »Promise FastTrak driver« and set it aside.


Preparing RedHat CDs

NOTE: If you already have Red Hat Linux CDs, skip this step. Otherwise, read this step to learn how you can get them for free.

  1. Logon to a Windows computer that has a CD Writer drive installed and setup properly. Insert a blank CD-R into the CD Writer.

  2. Point your browser to the Red Hat Web site: ftp://ftp.redhat.com/pub/redhat/linux/7.3/en/iso/i386/.

  3. Browse and locate disc1.iso (actual file name may be something-disc1.iso), and save this file to your Windows desktop.

  4. Right-click on the iso image created on your desktop and choose "Record to CD" It will then write the iso image onto your CD-R and create disk-1.

  5. Repeat the procedure for the second and third iso files (something-disc2.iso, something-disc3.iso) at ftp.redhat.com/pub.

  6. Test to make sure your CD-Rs are indeed readable. If you click on »My Computer« and click on the CD Writer Drive icon, you should be able to browse the contents of the CD-R.

  7. Label the CD-Rs properly: disc-1, disc-2 etc.


Installing Red Hat

Once you have created your CDs, you are ready to begin installing Red Hat on your Linux system.

  1. Restart the computer and press Cntrl-F when you see FastTrak BIOS prompt on screen. This will take you into the Promise FastTrak BIOS.

  2. Inside this BIOS, choose "delete array," "define array," and "choose Mirror."

  3. Press Cntrl-Y to save.

  4. Choose »Create Only« and ESC to reboot. When it reboots, you should see that Promise FastTrak now has 1x2 RAID Mirror defined over your two hard disks connected to FastTrak controller.

  5. Insert your Red Hat boot disk (disk-1) into your CD-ROM and reboot.

  6. At the boot-prompt, type:

    linux noprobe

  7. Now, installation will begin. Choose »Add device« and scroll through the list of available drivers to see if Promise FastTrak is listed. If it is not listed, press F2 to load external driver from a floppy. Insert your Promise FastTrak driver floppy and hit "OK."

  8. Continue with installation. Choose only ext3 type partitions for now. You can make ext2 partions at the very end, if you really need them.

  9. When the system you to create Boot Floppy, insert a blank floppy disk. The Red Hat installation program will create a Boot Floppy disk.

    NOTE: Please do not click on »Skip boot disk creation«. If you skip this step and do not create a Boot Floppy disk, you will be very sorry later.

  10. When the install asks you to choose Boot loader configuration, please choose »LILO only«. Do not choose »GRUB« as your boot loader.

    When the installation is finished, you will see »Congratulations« screen.

  11. Press Cntrl-ALT-F2 to switch to tty2.

  12. At the shell prompt, type:

    cd /mnt/sysimage/lib/modules/2.4.18-3/kernel/drivers/scsi

  13. Type ls and make sure the file ft.o exists. If not, you are going to need to manually install the module ft.o as follows:

    1. Make sure your Driver floppy is mounted. Go into the floppy and type

      mv module.cgz /tmp 
      cd /tmp 
      gzip -dc module.cgz | cpio -idumv 

    2. Now, you will see a bunch of directories created under /tmp.

      cd /tmp/`uname -r` 
      cp ft.o /mnt/sysimage/lib/modules/`uname -r`/kernel/drivers/scsi

    3. At the shell prompt, type:

      less /mnt/sysimage/etc/lilo.conf

      Check to see that the lilo.conf looks good. Especially, it should have the initrd= line and the corresponding initrd.img file must exist in /mnt/sysimage/boot. If not, you are going to create it manually as follows:

      /mnt/sysimage/usr/sbin/chroot /mnt/sysimage /sbin/mkinitrd \
      --preload jbd \ 
      --preload ext3 \ 
      --preload scsi_mod \ 
      --with ft \ 
      /boot/initrd.img 2.4.18-3

  14. Now, remove the floppy and the CD, and reboot. At this point, pray that your computer will boot without any problems.

  15. If it does not boot, insert your Boot Floppy and reboot and login; And then repair as follows:

    1. Make sure /boot/initrd.img exists. Make sure /lib/modules/2.4.18-3/kernel/drivers/scsi/ft.o exists (If not you have to manually fix these issues as explained above)

    2. Type: /sbin/lilo

    3. Now, remove floppy and reboot. Your machine should boot into your new machine now using Promise Driver.

  16. Type df -k and you should see your hard disks as /dev/sdaX instead of /dev/hdaX. This is because the Promise Driver is actually a special type of Software Emulation RAID, not exactly Hardware RAID. (Promise RAID works through a BIOS Hack).

If your machine is SMP, you will have to manually create initrdsmp.img, when you boot into Uniprocessor Kernel as shown below, and edit /etc/lilo.conf and then test to see you can boot into SMP system.

  1. When you boot your machine into 2.4.18-3 uniprocessor kernel, type the following to make initrdsmp.img to be used for 2.4.18-3smp kernel:

    /sbin/mkinitrd \
    --preload jbd \ 
    --preload ext3 \ 
    --preload scsi_mod \ 
    --with ft \ 
    /boot/initrdsmp.img 2.4.18-3smp

    NOTE: If you are tired of remembering the command to create initrd files, dowload my geninitrd script and keep it handy.

  2. Adjust your /etc/lilo.conf accordingly for 2.4.18-3smp (the SMP kernel section), type /sbin/lilo and reboot into the SMP kernel. Here is what /etc/lilo.conf should look like.

At this point, you have a working Red Hat machine with SMP support, if applicable. If you are happy with the fact that you are running a fake Hardware RAID from Promise FastTrak using SCSI Emulation, then read no further.

Because Promise Driver is a SCSI emulation, it puts a lot of load on CPU(s). Read on if you want to enable true Linux native RAID and get rid of this Promise SCSI emulation.


Installing Native Linux RAID

The first step you want to take is to configure your networking and connect your computer to Internet, which is still running under Promise Driver SCSI emulation. Next you will install native Linux RAID.

  1. Login as root. Go to www.kernel.org and download latest kernel 2.4.19.tar.gz into /root.

  2. Configure your kernel:

    cd /usr/src/ 
    tar xvzf /root/linux-2.4.19.tar.gz 
    cd linux-2.4.19          # cd to kernel source directory just created by tar
    cp config.txt .config    #(See NOTE below to find out where to get config.txt)
    make menuconfig

    NOTE: You can download a working config.txt file HERE. This is a generic kernel configuration file with all the necessary options turned on for Promise FastTrak and HighPoint HPT RAID systems. You can, of course, modify this to suit your needs either directly in a text editor or by typing make menuconfig as explained above. It is easy to make mistakes if you are editing .config directly in vi or emacs. Therefore, it is recommended to use Menu Interface by typing make menuconfig.

  3. Enable all the following in the kernel statically (NOT as modules):

      Code maturity level options --->
      	[*] Prompt for development and/or incomplete code/drivers
      ATA/IDE/MFM/RLL Support --->
    	<*> ATA/IDE/MFM/RLL Support
    	IDE/ATA/ATAPI Block Devices --->	
    	<*>    Enhanced ATA/IDE/MFM/RLL disk/cdrom/tape/floppy support
    	<*>        Include IDE/ATA-2 Disk Support
    	[*]            Use multi-mode by default
    	<*>        Include IDE/ATAPI CDROM support
    	[*]        Generic PCI IDE chipset support
    	[*]            Sharing PCI IDE interrupt support
    	[*]            Generic PCI Bus master DMA support
    	[*]                Use PCI DMA by default when available
    	[*]            Intel PIIXn chipset support
    	[*]                PIIXn tuning support
    	[*]            Promise PDC202{46|62|65|67|68} support
    	[*]                Special UDMA Feature
    	[*]                Special FastTrak Feature
    	[*]            VIA 82CXXX chipset support
    	<*>    Support for IDE RAID controllers
    	<*>        Support Promise software RAID (Fasttrak(tm))

  4. After you have enabled static features as shown above, make any more changes that you would like to make to suit your environment.

  5. Save the kernel configuration. It is saved to .config in the current directory. Please back up this file. If you dont do so, you will regret it later. Copy .config file in a blank floppy or in /root

  6. Build and install the kernel like you normally do, by typing:

    make dep ; make clean ; make && make install 
    make modules && make modules_install

Look at /etc/lilo.conf to make sure new lines are added to boot your new kernel 2.4.19. Note that there should not be an initrd= line for this new kernel in /etc/lilo.conf. That is, our new kernel will boot itself without depending on a initrd.img unlike your current 2.4.18-3 kernel.

Now adjust /etc/lilo.conf as follows:

  1. Locate the root=/dev/sdaX line for the new kernel in /etc/lilo.conf. Change this to root=/dev/ataraid/d0pX where X is a number 1 through 16. Save your changes.

  2. Type:

    /sbin/lilo

  3. If you chose any ext2 partitions during installation, you should comment them out in /etc/fstab for now.(Best thing is: Forget ext2 in this whole process)

  4. Remove all floppies and CDs, and reboot by typing:

    sync;sync;reboot

  5. At the LILO prompt, type your new kernel lable corresponding to 2.4.19. Your computer should then boot into your new kernel.

    NOTE: If it does not boot, then insert Boot Floppy disk (which you prepared during installation process) and reboot. Your computer should then boot into your old SCSI emulated RAID configuration using old kernel. Login to your Linux machine and determine your Append Line, see Section 7.2. Then, modify your /etc/lilo.conf to include the Append Line as illustrated in Step 2 of Section 7.2. Finally, activate changes by typing /sbin/lilo and reboot by typing sync;sync;reboot. When you see LILO prompt, type your new kernel lable corresponding to 2.4.19.

  6. Login as root and type df -k to make sure you see /dev/ataraid/d0X entries instead of earlier /dev/sdaX entries.

    NOTE: You may see some errors related to mounting swap device at the time of booting into new kernel. These are harmless. You should edit /etc/fstab to change any sdaX entries to ataraid/d0pX entries.

  7. Now, connect your computer to Internet and download lilo-22.tar.gz (the latest version of lilo program) from the Internet.

  8. Remove the existing lilo on your computer by typing: rpm -e --nodeps lilo

  9. Install new version of lilo as follows:

    tar xvzf lilo-22.tar.gz
    cd lilo-22	# cd to lilo source directory just created by tar 
    ./QuickInst.sh 

  10. Say "Yes" to questions the system will ask you.

  11. Ignore any errors except if /sbin/lilo is not created.

  12. Adjust /etc/lilo.conf as follows:

    • Replace linear by lba32

    • Delete line "compact"

    • Change vga= line to vga=normal

    • Change boot=/dev/sda line to boot=/dev/ataraid/dN (where N is the partition number on which your root file system exists. Type df -k / to find out your root partition number).

    • Make sure that default=linux-2.4.19 (where linux-2.4.19 is the label given to boot your new kernel: 2.4.19)

  13. Save changes to the file and type: /sbin/lilo

  14. Reboot the system and cross your fingers.

Here is what the final /etc/lilo.conf should look like.

If everything comes up without any errors, time to celebrate!!


Installing on an existing Linux system

This section explains how to install Linux Native ATA RAID on non-OS disks you may have on a running Linux machine. Non-OS disks are those which do not contain any Linux OS partitions such as /, /usr, /var, /boot. In other words, we have a working Linux machine with two free disks and we want to setup ATA RAID mirror (raid 1) on those two disks. When we save important data on such a mirror device, our data is protected. Ofcourse, like any other RAID 1, we will experience improved read speeds while reading the data and slightly decreased write speeds while modifying or adding new data to the mirror device. Therefore, using RAID 1 for data disks is recommended if the data disk is more frequently read than written to. A web server hosting rarely changing web sites is a good example where web content is rarely modified but very frequently accessed by users.

Here are the steps to install non-OS ATA RAID if your RAID chip is from Promise Technology:


Append Line

For the purpose of understanding various tasks involving Promise FastTrak RAID such as upgrading or troubleshooting, we introduce a noun: Append Line

All the ide options you pass at the LILO boot: prompt at the time of booting, when put together as a string, make up the Append Line. All the ide options in double quotes after append= keyword in /etc/lilo.conf also make up the Append Line.

For example, if you type

linux-new ide2=0x0001,0x0009,9 ide3=0x2000,0x2009,10 ide4=none nousb expert root=/dev/hda3

at boot: prompt at the time of booting your Linux computer, then Append Line is the string

ide2=0x0001,0x0009,9 ide3=0x2000,0x2009,10 ide4=none.

Similarly, if your /etc/lilo.conf has the following section, your Append Line is

ide2=0x9400,0x9002 ide3=0x8800,0x8402.

image=/boot/vmlinuz-2.4.9-10
	label=linuxold
	read-only
	root=/dev/hde9
	append="nousb ide2=0x9400,0x9002 ide3=0x8800,0x8402"
	initrd="initrd.img"

When we experience problems booting a Linux machine with RAID, we may have to use an appropriate Append Line. Therefore, it is important to determine and write down the Append Line. This will help you fix your problems later or upgrade your kernel smoothly or add/remove additional hard disks.


Determining the Append Line

To determine the correct Append Line, we should first know how all our ide devices are connected. IDE devices can be hard disks, ATAPI CDROM(s) etc. Once we determine the Append Line, we can append it to the boot: options (at the time of booting) or we can alternatively assign it as a string value to the append paramater in /etc/lilo.conf. Unless you love to remember complicated boot: options and type them at boot time every time, you should choose the second method, i.e., insert it into /etc/lilo.conf . You can do so by inserting append="Your Append Line Here", saving file and then activating new /etc/lilo.conf by running the command /sbin/lilo.

For the purpose of understanding better, lets say that your ide devices are as follows:

  • ide0: hda , hdb (hard disks)

  • ide1: hdc , hdd (hard disks or other ide devices like CDROM)

  • ide2: hde (first free disk)

  • ide3: hdg (second free disk)

The two free disks above (hde and hdg) are the ones we would like to setup as RAID 1 to create /dev/ataraid/d0 raid device. Note that we do not have hdf or hdh because that is how we used the IDE/RAID ports on Promise chip. It is not a good idea to connect two hard disks to the same Promise controller IDE port. In the above example, we used Primary Master and Secondary Master connections on the Promise Technology card.

If you do not know how various ide devices are connected in your computer, take a look at /proc/devices and /proc/ide/*. You can also carefully go through boot log file, /var/log/bootlog (or type dmesg | more right after your Linux system boots) to find your ide devices. Now type less /proc/pci and locate appropriate information about Promise Technology. In the output of less /proc/pci, you can see somewhere information about your Promise chip, something like:

 Bus  0, device  17, function  0:
    Unknown mass storage controller: Promise Technology Unknown device (rev 2).
      Vendor id=105a. Device id=d30.
      Medium devsel.  IRQ 10.  Master Capable.  Latency=32.  
      I/O at 0x9400 [0x9401].
      I/O at 0x9000 [0x9001].
      I/O at 0x8800 [0x8801].
      I/O at 0x8400 [0x8401].
      I/O at 0x8000 [0x8001].
      Non-prefetchable 32 bit memory at 0xd5800000 [0xd5800000].

From this output, we learn that our Promise Technology card uses IRQ 10 for both ide ports (ide2 and ide3). Using same IRQ is perfectly alright as long as your kernel supports PCI IRQ Sharing. By default, our Linux kernel is configured to support PCI IRQ sharing. From the above output, we also learn that our Promise Technology card uses various IO addresses. For the purpose of identifying Promise Technology disks properly at boot time, we only want the IRQ number(s) and the first four IO Address numbers outside [ ]. Write down on a piece of paper this information. In this case, from the above output:

IRQ1 = 10
IRQ2 = 10
IO1 = 0x9400
IO2 = 0x9000
IO3 = 0x8800
IO4 = 0x8400

Now, we have to evaluate the following to obtain the correct Append Line. Then either specify this Append Line at boot time or specify it in lilo configuration file.

ideX=IO1,IO2+0x0002,IRQ1 ideY=IO3,IO4+0x0002,IRQ2
where ideX and ideY are the two IDE ports of Promise card our free disks are using.

In our example, the above Append Line will become:

ide2=0x9400,0x9002,10 ide3=0x8800,0x8402,10

If, for example, we want to boot kernel version 2.4.19, labelled linux according to /etc/lilo.conf, then we specify our Append Line in one of the following two methods:

  1. At boot time

    boot: linux ide2=0x9400,0x9002,10 ide3=0x8800,0x8402,10
    If you choose this method, you should manually type the Append Line after the kernel label linux everytime you boot your Linux machine.

  2. In /etc/lilo.conf

    image=/boot/vmlinuz-2.2.19
    	label=linux
    	read-only
    	root=/dev/ataraid/d0p12
    	append="ide2=0x9400,0x9002,10 ide3=0x8800,0x8402,10"
    If you choose this method, you have to run lilo once to activate changes by typing /sbin/lilo. And you do not have to type anything extra at boot time.


Setting Up RAID 1

If you want to setup RAID 1 using Promise Technology proprietary driver (ft.o), you can download Promise Driver (ft.o) into /lib/modules/kernel-version and load the module by typing modprobe -k ft. You should then be able to access your new raid device as /dev/sdc or something like that. But if it does not work, then determine your Append Line and add it to /etc/lilo.conf. If you are setting up RAID on an existing Linux system and are using either Promise Technology ft driver or Linux native ataraid driver, then use of Append Line in /etc/lilo.conf is strongly recommended. Once you reboot with your new /etc/lilo.conf that contains Append Line, you can load either driver (ft.o from Promise Technology or ataraid.o, the Linux Native RAID module) to enable RAID except when your kernel has built-in ataraid support in which case you do not have to load ataraid module.

As Linux Native RAID is recommended, let us discuss that in detail. To setup Linux Native RAID on an existing Linux machine, insert Append Line into /etc/lilo.conf as explained above. Now, activate changes by typing /sbin/lilo. Then reboot your computer. After your computers reboots, load ataraid module manually if your kernel does not have ataraid built-in support or ataraid.o module failed to load for some reason. If you compiled your kernel with static ataraid support (ataraid not as module), then you can start formatting and using your mirror disk /dev/ataraid/d0 right away.

But if you compile ataraid as a seperate module, then type lsmod and see ataraid is listed. If not, manually load it by typing modprobe -k ataraid. If you dont see any errors, then you can start using your mirror disk /dev/ataraid/d0 right away. Format it, mount it and use it just like you normally do.

The fact that you can use /dev/ataraid/d0 implies that you are successful in your mission. Please do not access /dev/hde, /dev/hdg or any of their partitions directly, although Linux will let you do that. Once you make a mirror device from two disks, you should always access the mirror device and not the disks directly.


Upgrading Kernel

Read this section carefully before you plan to upgrade kernel on your Linux machine with Promise FastTrak RAID. Unless you are not using Promise FastTrak at all in any way, you need this information to avoid problems.

Always backup your data before kernel upgrade. Also backup /etc/fstab, /etc/lilo.conf, /boot/vmlinuz-currentversion and /boot/initrd.img (if you use initrd). When you upgrade your kernel, do not delete old kernel or its dependent files in /boot and do not delete the lines corresponding to it in /etc/lilo.conf. If you upgrade kernel to say 2.4.20, just create another kernel section in /etc/lilo.conf. For example, add the following lines to /etc/lilo.conf:


# Begin Code for booting my brand new kernel: 2.4.20

image=/boot/vmlinuz-2.4.20
	label=linux-new
	read-only
	root=/dev/ataraid/d0p12

# End Code for booting my brand new kernel: 2.4.20

Also, do not change default=linux line in /etc/lilo.conf unless and until you successfully can boot into your new kernel by typing linux-new at the boot: prompt (or highlighting linux-new in the menu, if you are using LILO in curses menu mode).

Now lets discuss the actual process of upgrading kernel in the following four cases:

  1. Promise Technology (ft) Driver with OS on RAID mirror

  2. Promise Technology (ft) Driver with non-OS data on RAID mirror

  3. Linux Native (ataraid) Driver with OS on RAID mirror

  4. Linux Native (ataraid) Driver with non-OS data on RAID mirror

OS stands for "Operating System" or more specifically Red Hat Linux Operating System in our case. When you install Linux on mirrored partitions such as /dev/ataraid/d0p1 (or /dev/sda1 when using Promise Technology proprietary driver), you are said to have your OS on RAID mirror. If your Linux machine has only the main partitions such as / and /boot on RAID, it is also called (a case of) OS on RAID.

Partitions created by user to make use of available free partitions such as /mydata1, /imp, /scratch are not part of Linux OS because Linux does not install any files into them by default when you install Linux or upgrade any standard Linux software package. Any data in such user partitions becomes user data or alternatively, non-OS data. It is a good idea to use only ext3 and swap file systems for OS partitions. For non-OS partitions, you can use other file systems such as ext2 and dos (if you have another operating system like Windows on the same Linux computer or if you just feel like you love dos so much). However, why do you want to use ext2 if you dont have to and you have a better choice of using ext3 for OS or non-OS partitions?


Promise Technology (ft) Driver with OS on RAID mirror

Currently, Promise Technology supports Red Hat 7.3 and earlier versions only. Red Hat 7.3 uses kernel 2.4.18-3 by default. Also note that, you have to use initrd.img (Initial RAM disk image) in /etc/lilo.conf, when you install Linux with Promise supplied driver. At the time of installation, Promise Driver scripts are supposed to automatically generate initrd file and configure /etc/lilo.conf for you. Unfortunately, this does not work properly and you may have to manually create initrd.img and configure /etc/lilo.conf yourself.

You are stuck with the default kernel 2.4.18-3 and you cannot and should not upgrade kernel either by compiling or by automatic update programs such as up2date or rpm utility. If you really, really want to upgrade kernel then do so but do not use raid. You can add Append Line to the /etc/lilo.conf as explained in Section 7.2 and do not load ataraid module (or do not compile your new kernel with ataraid feature built-in). By doing this, you are upgrading kernel to new version and sacrificing RAID feature because you are using Promise Technology card as a simple IDE extension card.

If Promise Technology releases new version of their ft driver for 2.4.19 in future, you can then upgrade your kernel first to 2.4.19 (using up2date or rpm but not by manually compiling) and place their new version of ft.o file in /lib/modules/kernel-2.4.19. You will also have to put initrd-2.4.19 in /boot and append initrd= line to the new kernel section in /etc/lilo.conf. If your Linux machine uses Promise Technology driver, your OS is on RAID mirror and Promise Technology did not release any new versions for new kernel versions, please do not fool around with your current kernel. If you do fool around, remember that you can seriously damage your computer and not be able to boot or retrieve your data.


Promise Technology (ft) Driver with non-OS data on RAID mirror

Almost all of explanation in previous case (Promise Technology (ft) Driver with OS on RAID mirror) applies in this also, ofcourse you are now risking non-OS data instead of OS. That means, if your upgrade fails, you will be able to boot but not be able to see data in your RAID partitions. Additionally, you have the flexibility of loading and unloading Promise Proprietary driver (ft.o). However, this is not guaranteed to work smoothly because Promise Technology driver has a lot of issues.

Unless Promise Technology releases appropriate drivers for new kernel version, please do not attempt kernel upgrade in any method. You are stuck with 2.4.18-3 kernel. You may be required to add Append Line as discussed in Section 7.2 to boot your computer in some cases.


Linux Native (ataraid) Driver with OS on RAID mirror

You can upgrade kernel to any version above 2.4.18 by recompiling the kernel and not by any automatic upgrade method such as up2date or rpm utility. You need .config file from your previous kernel source directory (/usr/src/linux-2.4.18/.config). You did save your 2.4.18 .config file, didn't you?

After you copy .config into /usr/src/linux-2.4.19 directory, you may make changes by typing make menuconfig but generally you do not need to make changes because you are upgrading only to 2.4.19 and your machine hardware did not change. But if you do make changes by typing make menuconfig, remember to save and also backup your modified .config file. Save the .config file safely in /root or on a floppy disk. Here are the steps:

  • Unzip new kernel in /usr/src and rename top directory to linux-2.4.19. So your new kernel source directory is /usr/src/linux-2.4.19.

  • cp /root/config.txt .config

  • make menuconfig (Make any required changes)

  • cp .config /root/config-2.4.19.txt (Back up config file in a safe place)

  • make dep ; make clean ; make && make install (Install new kernel)

  • make modules && make modules_install (Install new kernel modules)

  • Edit /etc/lilo.conf to add new lines to boot new kernel. Label the new kernel linux-new. Do not change default= line and do not delete lines corrosponding to current working kernel.

  • /sbin/lilo (Activate changes in /etc/lilo.conf)

  • /sbin/lilo -R linux-new (Tell LILO to treat linux-new as default boot kernel just for one time only)

  • sync;sync;reboot (Reboot and hope that it works. If it does not boot, power off and power on again. Then login and investigate why your new kernel did not boot.)


Linux Native (ataraid) Driver with non-OS data on RAID mirror

To upgrade kernel in this case, follow same procedure as explained in previous section (Linux Native (ataraid) Driver with OS on RAID mirror). If you experience problems, you may be required to add an additional line, Append Line, to your /etc/lilo.conf. To find out what your Append Line is, see Section 7.2.

Similar to previous case, do not attempt to upgrade kernel by any automatic method (up2date or rpm utility). Manually compile and your install your new kernel as explained in the previous section.


Disabling RAID feature on Promise FastTrak

If you are reading this section, then you may be sick and tired of the fake RAID feature (formally known as quasi-hardware RAID) provided by Promise Technology FastTrak card or onboard chip on your motherboard.


Case 1: OS not using RAID

It is possible to disable the RAID feature and use the Promise FastTrak as a plain vanilla IDE card. It is very simple. Follow the below steps:

  1. Determine your Append Line. See Section 7.2 for help with this

  2. Modify /etc/lilo.conf to include append="Append Line" in your current kernel boot section. Again see Section 7.2 for details.

  3. Type /sbin/lilo and reboot

Now you should see your hard disks seperately and you can use them. If you previously had partitions on the RAID mirror, you will see partitions accordingly on each of the two member disks. You will also see the data that you previously stored on the RAID mirror.


Case 2: OS is using RAID

If you want to disable RAID on a Linux computer that is using RAID mirror partitions for /, /boot, /usr etc., then first backup your data including /usr/src/linux/.config, /etc/fstab, /boot/vmlinux. Power off your computer. Then turn it on. At the boot: prompt, type linux followed by Append Line. If your system does not boot successfully, then insert your emergency rescue/boot floppy disk, boot off of that floppy disk and type at the boot: prompt linux followed by Append Line. If you still cannot boot, then you cannot disable RAID non-destructively, which means you have to boot off of the RedHat CDROM #1 and re-install Linux, again by typing linux followed by Append Line at the boot: prompt.

If your Linux machine boots successfully, then first make sure that all data is available and clean. Make sure that files in /boot are not corrupt. In some cases, the ASCII configuration files in /boot and LILO binary files may be corrupt. If that happens, you have to restore them from backup or reconfigure /etc/lilo.conf, run /sbin/lilo and recompile and reinstall the kernel (recompile with unmodified .config, i.e., without Promise RAID support).

If your Linux machine boots up and all files are safe, then add Append Line to /etc/lilo.conf, run /sbin/lilo and reboot.

If you disabled RAID on OS disks and then later changed your mind, then you have to back up data and reinstall Linux. If you change mind this way and want your RAID back on your Linux OS disks, you may have to sacrifice your current data.


Tips and Important Notes


For more information

For more information, please check the following resources


Appendix A. How is this document generated

So you want to know how I generated this HOWTO? Or, did you download SGML version of this document, modified some portions in it and now want to know how you can create HOWTO?

I made sure there are no errors in my SGML by first typing the command nsgmls -s ataraid.sgml. I created a script called makehowto and ran the command ./makehowto ataraid.sgml. Here is the my makehowto script:

#!/bin/bash
#
# makehowto by Murty Rompalli
# (c) All Rights Reserved
# Free for non commercial use. All other uses must be authorized explicitly
# by the creator. Contact me for more info. murty@solar.m u r t y.net
#

function maketut() {
echo;echo Creating Tutorial Files ...
jade \
    -t sgml \
    -d /usr/lib/sgml/stylesheets/nwalsh-modular/html/ldp.dsl\#html \
    $1.sgml 
}

function makehtml {
echo;echo Creating html file: $1.html ...
jade \
    -t sgml \
    -d /usr/lib/sgml/stylesheets/nwalsh-modular/html/docbook.dsl \
    -V nochunks \
    $1.sgml > $1.html 
}

function maketxt {
	if [ -f $1.html ]
	then
		echo;echo Creating text file: $1.txt ...
		lynx -dump $1.html > $1.txt
	else
		echo;echo $1.html not found, creating ...
		makehtml $1
		maketxt $1
	fi
}

function makepdf {
	[ -f $1.ps ] && gzip $1.ps

	if [ -f $1.ps.gz ]
	then
		echo;echo Creating pdf file: $1.pdf ...
		gzip -dc $1.ps.gz | 
		gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=$1.pdf -
	else
		echo;echo $1.ps.gz not found creating ...
		makeps $1
		makepdf $1
	fi
}

function maketex {
echo;echo Creating TeX file $1.tex ... 
jade \
    -t tex \
    -d /usr/lib/sgml/stylesheets/cygnus-both.dsl\#print \
    $1.sgml
gzip $1.tex
echo $1.tex gzipped to $1.tex.gz
}

function makedvi {
echo;echo Creating DVI file $1.dvi ...
db2dvi $1.sgml  >/dev/null 2>&1
echo See $1.log for errors
gzip $1.dvi
echo $1.dvi gzipped to $1.dvi.gz
}

function makeps {
echo;echo Creating PS file $1.ps ...
db2ps $1.sgml  >/dev/null 2>&1
echo See $1.log for errors
gzip $1.ps
echo $1.ps gzipped to $1.ps.gz
}

#### Begin Main Program

echo "
makehowto utility for generating HOWTO from SGML file.
(c) Murty Rompalli
"

[ x$1 = x ] && 
echo "Error. Usage: $0 abc.sgml '{tut|html|pdf|tex|dvi|ps|all}'

Option 'all' is default if sgml file is the only option supplied.

Options:
-------
tut	Make complete tutorial, i.e., generate necessary html files
html	Make a printable single HTML file
pdf	Make a PDF file
tex	Make a TeX source file, gzipped
dvi	Make a DVI file, gzipped
ps	Make a PostScript file, gzipped
all	Generate all possible formats.

" && exit

file="`echo $1|sed 's/\.sgml$//'`"

[ x$file = x ] && 
echo Error. Usage: $0 abc.sgml '{tut|html|tex|dvi|ps|all}' && exit

[ -f $file.sgml ] || {
echo Error. $file.sgml does not exist
exit
}

[ -r $file.sgml ] || {
echo Error. $file.sgml not readable
exit
}


if [ x$2 = x ]
then
	action=all
else
	action=$2
fi 


case $action in
tut|tutorial) maketut $file  
		;;
html|htm) makehtml $file  
		;;
tex|latex) maketex $file 
		;;
dvi) makedvi $file 
		;;
ps) makeps $file 
		;;
text|txt) maketxt $file
		;;
pdf) makepdf $file
		;;
all) 	maketut $file  
	makehtml $file  
	maketex $file  
	makedvi $file
	makeps $file
	maketxt $file
	makepdf $file
	;;
*) echo error 
	;;
esac

\rm -f $file.aux
\rm -f $file.tex
\rm -f $file.dvi

echo;echo makehowto: Finished
echo You can review $file.log and delete it.
echo Thank you for using makehowto.
echo

You can also just type ./makehowto ataraid.sgml pdf, for example, if you just want create PDF version. Just type ./makehowto to get more help on using the script. Click here to download this makehowto script.


Appendix B. What if you have HighPoint HPT instead of Promise FastTrak RAID?

If your computer has HighPoint HPT RAID instead of Promise FastTrak RAID, you can still follow this document with a few modifications:

If you want to upgrade kernel, install on an existing system etc., then you can follow Chapter 7 and all other chapters that come after that chapter in this document.